Re: [Xen-devel] [PATCH 5/5] xen/pcifront: Use Xen-SWIOTLB when initting if required.

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

On Thu, 16 Aug 2012, Konrad Rzeszutek Wilk wrote:
> We piggyback on "xen/swiotlb: Use the swiotlb_late_init_with_tbl to init
> Xen-SWIOTLB late when PV PCI is used." functionality to start up
> the Xen-SWIOTLB if we are hot-plugged. This allows us to bypass
> the need to supply 'iommu=soft' on the Linux command line (mostly).
> With this patch, if a user forgot 'iommu=soft' on the command line,
> and hotplug a PCI device they will get:
> 
> pcifront pci-0: Installing PCI frontend
> Warning: only able to allocate 4 MB for software IO TLB
> software IO TLB [mem 0x2a000000-0x2a3fffff] (4MB) mapped at [ffff88002a000000-ffff88002a3fffff]
> pcifront pci-0: Creating PCI Frontend Bus 0000:00
> pcifront pci-0: PCI host bridge to bus 0000:00
> pci_bus 0000:00: root bus resource [io  0x0000-0xffff]
> pci_bus 0000:00: root bus resource [mem 0x00000000-0xfffffffff]
> pci 0000:00:00.0: [8086:10d3] type 00 class 0x020000
> pci 0000:00:00.0: reg 10: [mem 0xfe5c0000-0xfe5dffff]
> pci 0000:00:00.0: reg 14: [mem 0xfe500000-0xfe57ffff]
> pci 0000:00:00.0: reg 18: [io  0xe000-0xe01f]
> pci 0000:00:00.0: reg 1c: [mem 0xfe5e0000-0xfe5e3fff]
> pcifront pci-0: claiming resource 0000:00:00.0/0
> pcifront pci-0: claiming resource 0000:00:00.0/1
> pcifront pci-0: claiming resource 0000:00:00.0/2
> pcifront pci-0: claiming resource 0000:00:00.0/3
> e1000e: Intel(R) PRO/1000 Network Driver - 2.0.0-k
> e1000e: Copyright(c) 1999 - 2012 Intel Corporation.
> e1000e 0000:00:00.0: Disabling ASPM L0s L1
> e1000e 0000:00:00.0: enabling device (0000 -> 0002)
> e1000e 0000:00:00.0: Xen PCI mapped GSI16 to IRQ34
> e1000e 0000:00:00.0: (unregistered net_device): Interrupt Throttling Rate (ints/sec) set to dynamic conservative mode
> e1000e 0000:00:00.0: eth0: (PCI Express:2.5GT/s:Width x1) 00:1b:21:ab:c6:13
> e1000e 0000:00:00.0: eth0: Intel(R) PRO/1000 Network Connection
> e1000e 0000:00:00.0: eth0: MAC: 3, PHY: 8, PBA No: E46981-005
> 
> The "Warning only" will go away if one supplies 'iommu=soft' instead
> as we have a higher chance of being able to allocate large swaths of
> memory.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>


Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

>  drivers/pci/xen-pcifront.c |   14 ++++++++++----
>  1 files changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
> index d6cc62c..ca92801 100644
> --- a/drivers/pci/xen-pcifront.c
> +++ b/drivers/pci/xen-pcifront.c
> @@ -21,6 +21,7 @@
>  #include <linux/bitops.h>
>  #include <linux/time.h>
>  
> +#include <asm/xen/swiotlb-xen.h>
>  #define INVALID_GRANT_REF (0)
>  #define INVALID_EVTCHN    (-1)
>  
> @@ -668,7 +669,7 @@ static irqreturn_t pcifront_handler_aer(int irq, void *dev)
>  	schedule_pcifront_aer_op(pdev);
>  	return IRQ_HANDLED;
>  }
> -static int pcifront_connect(struct pcifront_device *pdev)
> +static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
>  {
>  	int err = 0;
>  
> @@ -681,9 +682,13 @@ static int pcifront_connect(struct pcifront_device *pdev)
>  		dev_err(&pdev->xdev->dev, "PCI frontend already installed!\n");
>  		err = -EEXIST;
>  	}
> -
>  	spin_unlock(&pcifront_dev_lock);
>  
> +	if (!err && !swiotlb_nr_tbl()) {
> +		err = pci_xen_swiotlb_init_late();
> +		if (err)
> +			dev_err(&pdev->xdev->dev, "Could not setup SWIOTLB!\n");
> +	}
>  	return err;
>  }
>  
> @@ -699,6 +704,7 @@ static void pcifront_disconnect(struct pcifront_device *pdev)
>  
>  	spin_unlock(&pcifront_dev_lock);
>  }
> +
>  static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
>  {
>  	struct pcifront_device *pdev;
> @@ -842,10 +848,10 @@ static int __devinit pcifront_try_connect(struct pcifront_device *pdev)
>  	    XenbusStateInitialised)
>  		goto out;
>  
> -	err = pcifront_connect(pdev);
> +	err = pcifront_connect_and_init_dma(pdev);
>  	if (err) {
>  		xenbus_dev_fatal(pdev->xdev, err,
> -				 "Error connecting PCI Frontend");
> +				 "Error setting up PCI Frontend");
>  		goto out;
>  	}
>  
> -- 
> 1.7.7.6
> 
> 
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